<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
	.cart {
		position: relative;
		width: 120px;
		height: 40px;
		background-color: red;
	}

	.cart a {
		display: block;
		width: 100%;
		height: 100%;
	}

	.content {
		position: absolute;
		top: 0;
		left: 0;
		width: 300px;
		height: 100px;
		background-color: yellow;
	}
	</style>
</head>
<body>
	<div class="cart">
		<a href="">购物车</a>
		<div class="content"></div>
	</div>
</body>
</html>